Rugby players should be taught to tackle an opposing player who is carrying the ball around the lower trunk of the body in order to minimise the risk of concussion, according to the findings of a new study.

The study was carried out over a number of years by bioengineers at Trinity College Dublin, who carried out research to determine the optimum way to tackle that would reduce head injuries.

The team used a combination of video analysis, 3D motion analysis lab trials and model-based image matching techniques to assess how head impacts and movement vary based on the position on the body where tackles are made.

Among the findings of the work carried out by Associate Professor Ciaran Simms and PhD Researcher Gregory Tierney is that the risk of concussion is not the same for both the tackler and the ball carrier, with the tackler at higher risk of head injury.

They found that rather than the upper trunk or upper legs, tackling the lower trunk of the ball carrier's body, roughly around pelvis level, is more likely to prevent a head injury in the tackler.

"Our findings have helped us better understand the mechanisms of head impacts in rugby union and resulted in these recommendations, which we hope may guide prevention strategies and reduce HIA risks for athletes," said Professor Simms.

Tackler HIA due to tackling the upper trunk (left) and the upper legs (right)

47% of tackler Head Injury Assessments are the result of tackles to the upper trunk, with tackles to the upper legs causing 30%, the analysis found.

3D motion analysis lab trials were also carried out with professional players and model-based image matching techniques used to examine the effect of tackles at different points of the body.

A set of recommendations was then drawn up which for the tackler includes making contact at the lower trunk, taking shorter, faster steps when approaching the ball carrier and avoiding the planting of feet.

The research team also suggests that tacklers should keep their head up and face the ball carrier, should not look at the ground and should place their head on the correct side of the ball carrier.

Where to tackle? HIA risk areas

Concussion caused by high impact tackles to the upper trunk leading to damaging head motion in ball carriers can be reduced by half when the tackle connects around the mid or lower body trunk.

According to Mr Tierney the findings provide a basis for coaches to develop concussion prevention strategies.

"Furthermore, there needs to be a greater focus placed on safe contact technique in the tackle," he said.

"We identified easy-to-coach characteristics, such as keeping your head up, eyes on the ball carrier and feet active, that can really help reduce HIA risk. Surprisingly, these characteristics are not always exhibited by elite players."